A "cam-lock" is a coined name for a two part device that conveniently assembles and clamps, and unclamps and disassembles, mating foamed insulating panels. These panels are typically provided as the walls, roof and floor of large commercial coolers, freezers and other enclosures requiring high insulation. The cam-lock components are cast in and become a permanent part of a foamed panel.
The first, or the passive female, half of the cam-lock contains a pin fastened in a first housing component. The housing is configured to provide an operating clearance for and clamping of the latch, contained in the male part of the cam-lock. The housing must be made of sturdy materials to prevent the collapse of the void in the foam insulation created by the housing and to withstand the elevated temperatures and pressures during the expansion phase of the foam formation in the insulating panel manufacture process. Further, the housing becomes an essential structural part of the cam-lock assembly.
The second, or male, half of the cam-lock is similarly configured to hold the rotatable latch and cam. It is the active half of the two part device. The housing must be made of sturdy materials to prevent the collapse of the void in the foam insulation created by the housing and to withstand the elevated temperatures and pressures during the expansion phase of the foam formation in the panel manufacture process. This housing component becomes an essential structural part of the assembly.
It is essential that the latch of the enclosed cam/latch sub-assembly have a high and predictable frictional contact with the cam to prevent the latch from rotating about the cam unless it is deliberately rotated by an external force. This is to assure that the latch is in an "open" position to capture the pin in the female half of the cam-lock when assembling two mating panels. This is accomplished by adding a friction clutch device that operates from inside the cam to exert either axial or radial pressures between the latch and the cam.
Similarly, it is important that the cam/latch sub-assembly within the housing have a high and predictable frictional contact with the housing to prevent the sub-assembly from aimlessly rotating within the housing and possibly position itself as an obstruction to engaging the mating panels in preparation to be cammed together. This is typically attempted by maintaining close and tight manufacturing tolerances at the bearing points between the cam/latch sub-assembly and the enclosing housing.
For "hoop" strength in the completed structure, male and female cam-locks are typically joined together with a tie strap spanning the width of each panel. The tie straps that connect a male and female unit together are generally steel, attached to the cam-lock housing components by welding, riveting or other suitable fastening method.
The cam-lock is made by a number of different manufacturers in the U.S.A. and Europe. All share the same concept of making the housing and the internal parts as a working entity, requiring that the housing behave as a working structural part of the finished structure. Most housing components are made of steel, although there is at least one manufacturer that makes the housing in a sturdy, structural, plastic. Most have flanges for additional security in the panel.
The existing housing design has been manufactured for many years. The costs have been reduced to essentially the lowest possible value, and alternatives to reducing the cost further have proven elusive. Also the existing friction clutch design is unnecessarily complex and in existing installations permits the latch to move axially. Also difficulties in maintaining the manufacturing tolerances between the cam shaft and the housing bearing permit the cam/latch sub-assembly to freely rotate in some cam-locks. Finally where male and female tie straps are impractical, the security of the cam-lock is limited to the housing flanges.
According to the present invention a cam-lock is provided which overcomes the problems with existing cam-lock designs, as is reiterated above. According to the present invention the costs of the cam-lock are greatly reduced by reducing the cost of housings. The metal, typically steel, or structural plastic housings in the prior art are replaced by housing components of less expensive materials, such as cellulosic material or non-structural plastic. For example corrugated paper, paperboard, cardboard, or vacuum formed plastic, may be utilized for the housing component, permitting a dramatic reduction in material costs and labor. However structural integrity is maintained by utilizing particular flanges of metal (such as steel) or structural plastic (such as ABS), as the structural elements instead of the housing.
The problems with conventional friction clutches are also solved according to the present invention by providing an external friction clutch typically which provides a frictional force on the periphery of the cam, so that the latch rotates with the cam unless there is a definitive external force. Ties between adjacent cam lock assemblies are provided directly between the flanges, not to the housings. Neighboring cam-locks along the same edge of a panel can be mounted in a common flange, which dramatically improves strength in the finished panel. Also, to eliminate the undesirable free spinning of the cam/latch sub-assembly in the housing, according to the invention an external clutch is provided which impresses a substantially constant pressure on the protruding cam shaft.
According to one aspect of the present invention a latching assembly is provided comprising the following components: A latching pin mounted to a first flange or panel. A cam shaft, having a cam keeper positioned thereon, operatively mounted to a second flange or panel. The cam keeper having a substantially peripheral surface, a center, and an opening through which the cam shaft passes having the center thereof radially spaced from the cam keeper center. A latch having an opening therein for receipt of the cam keeper, the latch including a latch hook which cooperates with the latching pin to latch the first and second flanges or panels together. And, a friction clutch which supplies a radial or axial spring force from the exterior of the cam keeper to the cam keeper so as to provide frictional contact between the latch at the opening and the substantially peripheral surface of the cam keeper of sufficient magnitude and precision to ensure that the latch rotates with the cam shaft unless an external force is applied to deliberately rotate the latch with respect to the cam shaft.
The friction clutch preferably comprises a cantilevered tongue integral with the latch and having a portion thereof extending into spring-pressed engagement with the cam keeper peripheral surface. The tongue typically includes a thinned portion to provide flexibility thereof, and the latch is typically of metal (such as spring steel) or a sturdy but flexible plastic.
The latching assembly may further comprise a stop integral with the cam shaft and having a keeper pin extending axially outwardly therefrom substantially parallel to the cam shaft; and then the cam keeper has a keeper-pin receiving opening formed therein for receipt of the keeper pin to stabilize the position of the cam keeper on the cam shaft. The cam shaft typically comprises a non-round end surface (such as a hex or grooved structure) for engagement by a cooperating non-round tool element to effect rotation thereof.
Preferably the first and second flanges or panels comprise a first metal or structural plastic flange substantially integral with the latching pin, the latching pin extending in a direction of elongation with respect to the first flange; and a second metal or structural plastic flange which mounts the cam shaft for rotation about an axis substantially parallel to the direction of elongation of the latching pin. The assembly preferably further comprises a housing of primarily cellulosic material or non-structural plastic formed by cooperating first and second hollow housing components each having first and second faces, the first metal flange engaging the first and second faces of the first housing component, and the second metal flange engaging the first and second faces of the second housing component, and the latching pin, latch, and cam disposed within the housing. The housing components preferably are male and female components of corrugated paper, paperboard, cardboard, or vacuum formed plastic. Foamed thermal insulation preferably encompasses each housing component except an open end portion thereof which cooperates with (e.g. abuts) the other hollow housing component.
The latching assembly may also further comprise an external clutch associated with the second metal or structural plastic flange and exerting a force on the cam shaft to maintain the cam shaft and the second metal or structural plastic flange together until the cam shaft is positively rotated with respect to the second flange by an external force. For example the external clutch may comprise a spring loaded tab integral (one-piece) with the second flange.
The latching assembly may comprise a first latching assembly, and the first latching assembly may be in combination with a second (or more) latching assembly substantially the same as the first latching assembly. Under these circumstances the first and second flanges may be elongated, and both the first and second latching assemblies are mounted to the first and second flanges spaced from each other in a dimension substantially perpendicular to the axis of rotation of the cam shafts, and so that the cam shafts of the first and second latching assemblies are substantially parallel to each other.
According to another aspect of the present invention a latching assembly is provided comprising the following components: A latching pin mounted to a first metal or structural plastic flange. A cam shaft operatively mounted to a second metal or structural plastic flange. A latch operatively connected to the cam shaft, the latch including a latch hook which cooperates with the latching pin to latch the first and second flanges together. And, the first flange substantially integral with the latching pin, the latching pin extending in a direction of elongation with respect to the first flange; and the second flange mounting the cam shaft for rotation about an axis substantially parallel to the direction of elongation of the latching pin. The details of the components are preferably as described above.
According to yet another aspect of the present invention a latching assembly is provided comprising the following components: A latching pin mounted to a first metal or structural plastic flange or panel. A cam shaft operatively mounted to a second metal or structural plastic flange. A latch operatively connected to the cam shaft, the latch including a latch hook which cooperates with the latching pin to latch the first and second flanges or panels together. And, an external clutch associated with the second metal or structural plastic flange or panel and exerting a force on the cam shaft to maintain the cam shaft and the second metal or structural plastic flange or panel together until the cam shaft is positively rotated with respect to the second flange by an external force. The external clutch typically comprises a spring loaded tab integral (one-piece) with the second flange or panel, and the rest of the components are preferably as described in detail above.
It is the primary object of the present invention to provide an improved latching assembly, such as for use in assembling and disassembling mating foamed insulation panels that comprise the walls, roof, and floor of large commercial coolers, freezers, or other enclosures requiring high insulation. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.